Transplantation of wild-type bone marrow into Smad4^Δ/Δ recipients resulted in anemia. Hemoglobin level, hematocrit, MCV, reticulocyte count, leukocyte count, and platelet count are shown. Three individual Smad4^Δ/Δ recipient mice (#1 [○], #2 [▵], and #3 [◇]) developed anemia with individual differences in severity and kinetics. *Significant differences at 4 weeks (P ≤ .03; Student t test). The values for the Smad4^fl/fl control recipient mice (▴) are shown as the mean of 6 mice with standard deviation. The error bars indicate standard deviation.